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<div class="title">samples/cpp/edge.cpp</div>  </div>
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<p>This program demonstrates usage of the Canny edge detector</p>
<p>Check <a class="el" href="../../da/d5c/tutorial_canny_detector.html">the corresponding tutorial</a> for more details</p>
<div class="fragment"><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d1/d4e/utility_8hpp.html">opencv2/core/utility.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d1/d4f/imgproc_2include_2opencv2_2imgproc_8hpp.html">opencv2/imgproc.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d6/d87/imgcodecs_8hpp.html">opencv2/imgcodecs.hpp</a>&quot;</span></div><div class="line"><span class="preprocessor">#include &quot;<a class="code" href="../../d4/dd5/highgui_8hpp.html">opencv2/highgui.hpp</a>&quot;</span></div><div class="line"></div><div class="line"><span class="preprocessor">#include &lt;stdio.h&gt;</span></div><div class="line"></div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d2/d75/namespacecv.html">cv</a>;</div><div class="line"><span class="keyword">using namespace </span><a class="code" href="../../d8/dcc/namespacestd.html">std</a>;</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> edgeThresh = 1;</div><div class="line"><span class="keywordtype">int</span> edgeThreshScharr=1;</div><div class="line"></div><div class="line"><a name="_a0"></a><a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> image, gray, blurImage, edge1, edge2, cedge;</div><div class="line"></div><div class="line"><span class="keyword">const</span> <span class="keywordtype">char</span>* window_name1 = <span class="stringliteral">&quot;Edge map : Canny default (Sobel gradient)&quot;</span>;</div><div class="line"><span class="keyword">const</span> <span class="keywordtype">char</span>* window_name2 = <span class="stringliteral">&quot;Edge map : Canny with custom gradient (Scharr)&quot;</span>;</div><div class="line"></div><div class="line"><span class="comment">// define a trackbar callback</span></div><div class="line"><span class="keyword">static</span> <span class="keywordtype">void</span> onTrackbar(<span class="keywordtype">int</span>, <span class="keywordtype">void</span>*)</div><div class="line">{</div><div class="line">    <a name="a1"></a><a class="code" href="../../d4/d86/group__imgproc__filter.html#ga8c45db9afe636703801b0b2e440fce37">blur</a>(gray, blurImage, <a name="a2"></a><a class="code" href="../../dc/d84/group__core__basic.html#ga346f563897249351a34549137c8532a0">Size</a>(3,3));</div><div class="line"></div><div class="line">    <span class="comment">// Run the edge detector on grayscale</span></div><div class="line">    <a name="a3"></a><a class="code" href="../../dd/d1a/group__imgproc__feature.html#ga04723e007ed888ddf11d9ba04e2232de">Canny</a>(blurImage, edge1, edgeThresh, edgeThresh*3, 3);</div><div class="line">    cedge = <a name="a4"></a><a class="code" href="../../d1/da0/classcv_1_1Scalar__.html#ac1509a4b8454fe7fe29db069e13a2e6f">Scalar::all</a>(0);</div><div class="line"></div><div class="line">    image.<a name="a5"></a><a class="code" href="../../d3/d63/classcv_1_1Mat.html#a33fd5d125b4c302b0c9aa86980791a77">copyTo</a>(cedge, edge1);</div><div class="line">    <a name="a6"></a><a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">imshow</a>(window_name1, cedge);</div><div class="line"></div><div class="line">    <a class="code" href="../../d3/d63/classcv_1_1Mat.html">Mat</a> dx,dy;</div><div class="line">    <a name="a7"></a><a class="code" href="../../d4/d86/group__imgproc__filter.html#gaa13106761eedf14798f37aa2d60404c9">Scharr</a>(blurImage,dx,<a name="a8"></a><a class="code" href="../../d1/d1b/group__core__hal__interface.html#ga9d2ee1a8334733dea7482a47a88e0f87">CV_16S</a>,1,0);</div><div class="line">    <a class="code" href="../../d4/d86/group__imgproc__filter.html#gaa13106761eedf14798f37aa2d60404c9">Scharr</a>(blurImage,dy,<a class="code" href="../../d1/d1b/group__core__hal__interface.html#ga9d2ee1a8334733dea7482a47a88e0f87">CV_16S</a>,0,1);</div><div class="line">    <a class="code" href="../../dd/d1a/group__imgproc__feature.html#ga04723e007ed888ddf11d9ba04e2232de">Canny</a>( dx,dy, edge2, edgeThreshScharr, edgeThreshScharr*3 );</div><div class="line">    cedge = <a class="code" href="../../d1/da0/classcv_1_1Scalar__.html#ac1509a4b8454fe7fe29db069e13a2e6f">Scalar::all</a>(0);</div><div class="line">    image.<a class="code" href="../../d3/d63/classcv_1_1Mat.html#a33fd5d125b4c302b0c9aa86980791a77">copyTo</a>(cedge, edge2);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga453d42fe4cb60e5723281a89973ee563">imshow</a>(window_name2, cedge);</div><div class="line">}</div><div class="line"></div><div class="line"><span class="keyword">static</span> <span class="keywordtype">void</span> help(<span class="keyword">const</span> <span class="keywordtype">char</span>** argv)</div><div class="line">{</div><div class="line">    printf(<span class="stringliteral">&quot;\nThis sample demonstrates Canny edge detection\n&quot;</span></div><div class="line">           <span class="stringliteral">&quot;Call:\n&quot;</span></div><div class="line">           <span class="stringliteral">&quot;    %s [image_name -- Default is fruits.jpg]\n\n&quot;</span>, argv[0]);</div><div class="line">}</div><div class="line"></div><div class="line"><span class="keyword">const</span> <span class="keywordtype">char</span>* keys =</div><div class="line">{</div><div class="line">    <span class="stringliteral">&quot;{help h||}{@image |fruits.jpg|input image name}&quot;</span></div><div class="line">};</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main( <span class="keywordtype">int</span> argc, <span class="keyword">const</span> <span class="keywordtype">char</span>** argv )</div><div class="line">{</div><div class="line">    help(argv);</div><div class="line">    <a name="_a9"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html">CommandLineParser</a> parser(argc, argv, keys);</div><div class="line">    <span class="keywordtype">string</span> filename = parser.<a name="a10"></a><a class="code" href="../../d0/d2e/classcv_1_1CommandLineParser.html#a190215863579a6d244dccfd261ee0224">get</a>&lt;<span class="keywordtype">string</span>&gt;(0);</div><div class="line"></div><div class="line">    image = <a name="a11"></a><a class="code" href="../../d4/da8/group__imgcodecs.html#ga288b8b3da0892bd651fce07b3bbd3a56">imread</a>(<a name="a12"></a><a class="code" href="../../d6/dba/group__core__utils__samples.html#ga3a33b00033b46c698ff6340d95569c13">samples::findFile</a>(filename), <a name="a13"></a><a class="code" href="../../d8/d6a/group__imgcodecs__flags.html#gga61d9b0126a3e57d9277ac48327799c80af660544735200cbe942eea09232eb822">IMREAD_COLOR</a>);</div><div class="line">    <span class="keywordflow">if</span>(image.empty())</div><div class="line">    {</div><div class="line">        printf(<span class="stringliteral">&quot;Cannot read image file: %s\n&quot;</span>, filename.c_str());</div><div class="line">        help(argv);</div><div class="line">        <span class="keywordflow">return</span> -1;</div><div class="line">    }</div><div class="line">    cedge.<a name="a14"></a><a class="code" href="../../d3/d63/classcv_1_1Mat.html#a55ced2c8d844d683ea9a725c60037ad0">create</a>(image.size(), image.type());</div><div class="line">    <a name="a15"></a><a class="code" href="../../d8/d01/group__imgproc__color__conversions.html#ga397ae87e1288a81d2363b61574eb8cab">cvtColor</a>(image, gray, <a name="a16"></a><a class="code" href="../../d8/d01/group__imgproc__color__conversions.html#gga4e0972be5de079fed4e3a10e24ef5ef0a353a4b8db9040165db4dacb5bcefb6ea">COLOR_BGR2GRAY</a>);</div><div class="line"></div><div class="line">    <span class="comment">// Create a window</span></div><div class="line">    <a name="a17"></a><a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">namedWindow</a>(window_name1, 1);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#ga5afdf8410934fd099df85c75b2e0888b">namedWindow</a>(window_name2, 1);</div><div class="line"></div><div class="line">    <span class="comment">// create a toolbar</span></div><div class="line">    <a name="a18"></a><a class="code" href="../../d7/dfc/group__highgui.html#gaf78d2155d30b728fc413803745b67a9b">createTrackbar</a>(<span class="stringliteral">&quot;Canny threshold default&quot;</span>, window_name1, &amp;edgeThresh, 100, onTrackbar);</div><div class="line">    <a class="code" href="../../d7/dfc/group__highgui.html#gaf78d2155d30b728fc413803745b67a9b">createTrackbar</a>(<span class="stringliteral">&quot;Canny threshold Scharr&quot;</span>, window_name2, &amp;edgeThreshScharr, 400, onTrackbar);</div><div class="line"></div><div class="line">    <span class="comment">// Show the image</span></div><div class="line">    onTrackbar(0, 0);</div><div class="line"></div><div class="line">    <span class="comment">// Wait for a key stroke; the same function arranges events processing</span></div><div class="line">    <a name="a19"></a><a class="code" href="../../d7/dfc/group__highgui.html#ga5628525ad33f52eab17feebcfba38bd7">waitKey</a>(0);</div><div class="line"></div><div class="line">    <span class="keywordflow">return</span> 0;</div><div class="line">}</div></div><!-- fragment --> </div><!-- contents -->
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